Gastric amylin expression: Cellular identity and lack of requirement for the homeobox protein PDX-1. A study in normal and PBX-1-deficient animals with a cautionary note on antiserum evaluation

The gene encoding amylin is implicated in the generation of amyloid in the islets of Langerhans of diabetics and is believed to be regulated by the ho meodomain transcription factor PDX-1. Although gastric mucosa also produces amylin, studies on its cellular site of production have yielded highly div ergent results, localizing this peptide to either gastrin, serotonin, or so matostatin cells or to combinations thereof. Using region-specific amylin a ntisera in combination with reverse transcriptase-polymerase chain reaction , we now document that the majority of cells expressing amylin correspond t o somatostatin cells. Only a small subpopulation of gastrin cells contained immunoreactive amylin. Studies of PDX-1-deficient mice, which fail to deve lop gastrin cells while possessing normal numbers of somatostatin cells, re vealed no detectable change in gastric amylin expression. These data show t hat neither normal gastrin cell development nor PDX-1 expression is needed for gastric amylin expression.